Means for inhibiting noise and slugging in refrigerant compressors



AL 3,387 774 SLUGGING IN GERANT COMPRESSORS 5 Sheets-Sheet 2 ET ND June1968 E. 1.. GANNAWAY MEANS FOR INHIBITING NOISE A REFRI Filed NOV. 21,1966 June 11, 1968 GANNAWAY ET AL 3,387,774

MEANS FOR INHIBITING NOISE AND SLUGGING IN REFRIGERANT COMPRESSORS FiledNov. 21, 1966 5 Sheets-Sheet 3 Z 9% e and? ite tts 3,387,774 MEANS FORii Ii-EIBiTiNG NGHSE AND SLUGGING IN REFREGERANT COMPRESSGRS Edwin L.Gannaway, Sidney, and Doyle K. Iiams, Fort Loramie, Gino, assignors toQOpeIand Refrigeration Qorperation, Sidney, Qhio, a corporation ofMichigan Fiied Nov. 21, I966, Ser. No. %,752 12 flaiins. (Ci. 239-232)ABSTRACT 01*" THE DESCLGSURE A combined noise rnufiiing and slugrejecting assembly is disclosed herein, installed in a gas compressor ofthe type which is direct-driven by an electric motor. Said assemblyconsists of a stationary housing of hollow annular form surrounding andradially outspaced from an extension shaft portion of the motor. Theannular mufiiing chamber has an outlet connected to the inlet of thecompressor, and has an annular inlet directed toward the armature andlocated in an area where a vortex is created by the rotating armature.Said inlet also includes elongated passage means leading into theannular mutiling chamber, The principal path of access of gas to suchinlet is via the space between the shaft extension and the mufiler,whereby entrained nongaseous components are thrown into the vortex andaway from the inlet, but the major gas flow is not required to flowthrough rotary parts. Both the inlet and the outlet of the chamber areso located and directed as to reduce transmission of noise to theexterior.

The present invention relates to refrigeration motorcompressorassemblies and particularly to improved means for reducing noise andpreventing liquid constituents from entering the compressor.

A related object is to provide a combined muffier and slug rejectorassembly which constitutes an improvement upon the invention disclosedin the copending patent appiication of Comstock and Gannaway, Ser. No.135,202, filed Aug. 31, 1961 now Patent No. 3,288,357, which is lessexpensive and yet performs more efliciently the functions indicatedabove and which attains other objects and advantages which will becomeapparent upon consideration of the present disclosure in its entirely.

In the drawing:

FIGURE 1 is a vertical sectional view of a motor-compressor assemblyconstructed in accordance with the present invention;

FIGURE 2 is a horizontal sectional plan view of the same, with the topof the hermetic container broken away;

FIGURE 3 is a vertical sectional view similar to the upper portion ofFIGURE 1 but showing a modified construction;

FIGURE 4 is a vertical sectional vie-w similar to FIG- URE 3, showinganother modified construction, and

FIGURE 5 is a plan view of the internal components of the embodiment ofFIGURE 4, with the casing removed and partially broken away.

Referring now to the drawing, and particularly to the embodiment ofFIGURES 1 and 2, reference character 1-0 designates an hermeticallysealed container within which a rigidly integrated direct-coupledcompressorelectric motor assembly is mounted upon suitable resilientsupporting means, the resilient supporting means, comprising springsinterposed between the motorcornpressor assembly and the container, notbeing illustrated fully and being well known in the art. Themotor-compressor assembly includes a rigid frame structure generallydesignated 12, a compressor generally designated 14 carried by a lowerportion thereof, and an electric motor assembly generally designated 15carried by the upper portion thereof. The electric motor includes anarmature 16 fast upon a shaft 18 Which is direct-coupled to and drivesthe crankshaft 26 of the compressor. The motor and compressor componentsper se may be of any suitable or well known construction and do not inthemselves constitute a part of the present invention.

At its upper extremity, the armature carries cooling fins 22. Thearmature is also provided with longitudinal passages 24. A rigidextension 19 of the shaft 18 projects upwardly into a stop collarrigidly secured to and projecting downwardly from the top wall of thecasing 19 coaxially with respect to shaft extension 19 of sub stantiallygreater diameter. Collar 25 coacts with extension 19 to limit rockingmovement of the motor compressor on its resilient mounting.

When the compressor is operating, the pistons 28 thereof reduce thepressure within the container. The refrigerant from the low side of therefrigerating system (not shown) is returned directly into the interiorof the casing 1d and normally occupies the space above the level of theoil 29. It is, of course, desirable to maintain a substantial quantityof oil in the bottom of the casing at all times.

As is well known, when the compressor starts up after having been idlefor a substantial period and under certain operating conditions, the oilfoams vigorously and liquid bubbles and slugs of oil and refrigerantrise in the foaming contents so that if the compressor inlet weredirectly exposed within the casing, liquid would enter the compressor.Entry of liquid constituents in this manner is highly undesirablebecause damage to the compressor valve mechanism and possible oilstarvation may occur as well as objectionable noise. Many structuralarrangements have been proposed, and a considerable numher have beenutilized. for the purpose of reducing the ability of liquid constituentsto enter the compressor inlet of hermetic motor-compressor unitsdesigned for refrigeration service. Some such arrangements have involveda considerable cost penalty and/0r undesirable characteristics such as atendency to generate noise or to increase the transmission of noise tothe exterior. The arrangement disclosed in Patent No. 3,288,357,mentioned previously, effectively prevents slugging of liquid While atthe same time providing a substantial reduction of compressor inletnoises, without introducing new noise-creating components having anymaterial effect upon the overall noise level, and the present inventionoperates in many respects upon similar principles, but still furtherreduces both noise and cost, while attaining improved compressormounting and other benefits.

As shown in FIGURES 1 and 2, a hollow annular container generallydesignated 30 is provided, forming an inlet muffler, rigidly supportedby the stator supporting studs 31. The mufiler chamber 33 is defined bya flat sheet metal bottom plate portion 34 and a crowned sheet metal topsection generally designated 35 having a cylindrical outer Wall 36rising from the periphery of the bottom plate portion 34, to which it issecured by tongues 37 bent to underlie plate portion 34. A recessedcentral portion 38 of the top section and which is of substantiallygreater diameter than the stop collar 35 forms a seat for a conicalspring 40 which constitutes a part of the spring suspension system forthe motor-compressor assembly and which, as will be seen, resists bothupward and lateral movement of such assembly.

The bottom plate portion 34 and crown portion 35 are provided withintegral concentric downturned necks 41, 42, respectively, radiallyspaced to define a narrow elongated annular downwardly directed entrancepassage 44 for the chamber 33 concentric with the normal operating axisand encircling and substantially larger than the shaft extension 19. Theinlet conduits 45 to the compressor are connected to the chamber 33, sothat all of the fluid entering the compressor must pass first throughthe inlet 44 and then through the mufiler chamber 33.

The position of the lower extremity of the inlet passage 44 is such thatit lies above but preferably relatively close to the natural vortexproduced in the foaming oil and refrigerant mixture by the rotation andcentrifuging action of the armature and cooling fins.

The majority of the gas enters the muffler chamber by passing downwardlythrough the passage 46 between shaft extension 19 and neck 42, passage46 being larger than the passage 44. This gas path over the top of theannular mufiler and thence downwardly through passage 46 issubstantially unobstructed and no gas is compelled to pass throughrotating vanes or surfaces. The heavier particles of oil and liquidwhich flow downwardly through passage 46 cannot make the sharp 180 turnrequired in order to enter the inlet 44, and therefore enter the vortex,where they are expelled with the other heavier components through thespace between the motor and mufHer.

Pulsations due to the intermittent flow effects induced in the inlettubes 4-5 by the reciprocating compressor mechanism are cushioned by therelatively great volume of the .mutlling chamber 33 and so are notctfectively transmitted to the exterior, and the cushioning effect ofthe chamber 33 also tends to render more uniform the rate of gas flowthrough the inlet passage 44, eliminating pulsations in passage 4d, andsuch action is aided by the inertia of the column of higher velocity inthe relatively long and restricted inlet 44. Inlet 44 is also directeddownwardly and entirely away from the sheet metal casing 10, so that therelatively small amount of noise which does emanate therefrom is noteffectively transmitted to the container to become exteriorly audible.

The modified construction shown in FIGURE 3 will be seen to be basicallysimilar to that of FIGURES 1 and 2. Corresponding parts are designatedby reference numerals which are similar but 100 integers higher and manyof these will not require detailed redescription. As shown in FIGURE 3the mufiler assembly 130 is mounted upon stator studs 131 which arerelatively shorter than the studs 31 of the first embodiment, and theinlet-defining neck portions 141, 142 extend downwardly into the spacesurrounded by the cooling fins 122. By such an interfitted mounting,where the operating characteristics and capacity (ordinarily smaller) ofthe compressor permit, the overall dimensions of the assembly areminimized. Preferably, the extent of such interfitting is limited tosuch degree that, as indicated previously, the lower end of the inlet144 is free of the vortex.

In the further modification illustrated in FIGURES 4 and 5, in whichparts corresponding to the first embodiment are designated by referencecharacters which are similar but 200 integers higher, the muffierchamber 233 is defined by a stationary enclosure of generally similarshape formed by a fiat sheet metal bottom plate portion 234 and a diecast upper portion 235 and supported as by bracket arms 231 integralwith the bottom plate from the motor stator bolts. The crowned upperportion 235 has a re-entrant central section 238 forming a seat for thehelico-conical spring 240 and a neck 242 extending downwardly to definea gas inlet passage 246 surrounding the shaft extension 219. In thisembodiment, the inner periphery of the annular bottom plate portion 234is not necked downwardly, however, the diameter of its central opening241 being somewhat greater than the outside diameter of the central neck242 of crown section 235 to define an annular inlet 244 flush with thebottom of plate section 234 and lying relatively close to the upper endof the armature.

tions 257 formed in the crown portion 235 of the muffler.

Lobe portions 257 are spaced approximately from each other and eachcontains two passages 255 extending substantially radially through andoutwardly from an inner wall 259 defining a central opening 258 lyingdirect ly above and substantially aligned with the inlet 244, wall 259blocking communication between inlet 244 and muffier chamber 233 exceptthrough the passages 255- The outer ends of passages 255 open into theinterior of muffler chamber 233 at positions angularly displaced fromthe inlet tubes 245 leading to the compressor. The higher velocitycolumns of gas in the restricted inlet passages 255 act similarly tothose created by the restricted inlets 44- and 144 of the previousembodiments, and are so positioned that any noise at the inlets thereofis effective ly shielded from the exterior, while pulsations therein arealso reduced by the cushioning effect of the large chamber section 233-What is claimed is:

1. In combination with a compressor having an inlet and a rotary driveshaft, means for Inufiling inlet noise and diverting heavierconstituents from the inlet comprising walls defining a stationaryannular muffler chamber having an outlet passage leading therefrom tosaid compressor inlet and having an elongated stationary inet passageleading to such chamber, the chamber being of larger cross section thaneither of said passages and the inlet passage having an entrance openingpositioned in an area from which heavier constituents are centri fugedin response to rotation of vortex-producing portions of the shaft.

2. A combination as defined in claim 1 wherein said chamber spacedlyencircles the shaft and said entrance opening is also of annular formand is defined by a Wall lying close to but spaced from the shaft.

3. A combination as defined in claim 1 including a motor having anarmature fast on said shaft and having a stator, and a casing enclosingsaid motor and compressor, said walls defining the muffler chamber beingcarried by the stator and spacedly encircling the shaft, said entranceopening to the inlet passage also being defined by stationary walls ofannular form and spaced from the shaft.

4. A combination as defined in claim 3 wherein the shaft extends throughand beyond the inner wall of the muffler chamber to a position close tothe casing for cooperation with stop means on the casing.

5. A combination as defined in claim 1 including a motor having anarmature fast on said shaft and having a stator, and casing enclosingsaid motor and compressor, said walls defining the mufiler chamber beingcarried by the stator and spacedly encircling the shaft, said entranceopening to the inlet passage also being defined by stationary walls ofannular form and spaced from the shaft, said entrance opening facing ina direction toward the rotor and away from the casing.

6. A combination as defined in claim 3 wherein the shaft extends throughand beyond the inner wall of the muffler chamber to a position close tothe casing for cooperation with stop means on the casing, said entranceopening facing in a direction toward the rotor and away from the casing.

7. A combination as defined in claim 3 wherein said inlet passage isdefined by a pair of concentric radially spaced walls connected at oneend to said mufiler chamber and open at the other end at a positionrelatively close to the rotor to define said entrance opening.

3. A combination as defined in claim 3 wherein said inlet passage isdefined by a pair of concentric radially spaced walls connected at oneend to said Inufiler chamber and open at the other end at a positionrelatively close to the rotor to define said entrance opening, andcentrifuging means on the rotor adjacent to but spaced from saidentrance opening, a substantially unobstructed space being left betweensaid muifler chamber walls and the casing and stator, and between theshaft and the inlet passage.

9. A combination as defined in claim 1 wherein said chamber is ofannular form and spacedly encircles the shaft and said entrance openingis also of annular form and is defined by a wall lying close to butspaced from the shaft, centrifuging means on the shaft adjacent to butspaced from said entrance opening, and a casing enclosing the compressorand said chamber walls and spaced from the latter whereby constituentsmay enter the entrance opening by passing between the casing and mufflerchamber walls and thence between the shaft and said walls.

19. A combination as defined in claim 2 wherein the inlet passagecomprises a double-walled neck encircling the shaft and connecting theentrance opening to the chamber.

11. A combination as defined in claim 3 wherein the walls defining themuffler chamber have portions which are spaced from one another in anaxial direction to different extents at different radial positions, andspring means reacting against said casing and walls and located by saiddifferently spaced portions.

12. A combination as defined in claim 3 wherein the walls defining themufiler chamber have portions which are spaced from one another in anaxial direction to different extents at different radial positions, saidinlet passage comprising a baffling section between portions of saidwalls having elongated restricted opening portions extendingtherethrough from the entrance opening to the chamber.

References Cited UNITED STATES PATENTS 2,228,364 1/1941 Philipp 230-583,081,935 3/1963 Geisenhaver 230-206 3,239,132 3/1966 Frank et al. 23058ROBERT M. WALKER, Primary Examiner.

